diff --git a/libc/assert.h b/libc/assert.h
index 96f190671..5ee54351d 100644
--- a/libc/assert.h
+++ b/libc/assert.h
@@ -15,7 +15,7 @@
 COSMOPOLITAN_C_START_
 
 void __assert_fail(const char *, const char *, int);
-void __unassert_fail(const char *, const char *, int);
+void unassert(const char *, const char *, int);
 
 #ifdef NDEBUG
 #define assert(x) ((void)0)
@@ -32,14 +32,14 @@ void __unassert_fail(const char *, const char *, int);
 #ifndef NDEBUG
 #define unassert(x) __assert_macro(x, #x)
 #define npassert(x) __assert_macro(x, #x)
-#define __assert_macro(x, s)                  \
-  ({                                          \
-    if (__builtin_expect(!(x), 0)) {          \
-      __unassert_fail(s, __FILE__, __LINE__); \
-      __asm__("nop");                         \
-      __builtin_unreachable();                \
-    }                                         \
-    (void)0;                                  \
+#define __assert_macro(x, s)             \
+  ({                                     \
+    if (__builtin_expect(!(x), 0)) {     \
+      (unassert)(s, __FILE__, __LINE__); \
+      __asm__("nop");                    \
+      __builtin_unreachable();           \
+    }                                    \
+    (void)0;                             \
   })
 #else
 #define npassert(x)                  \
diff --git a/libc/calls/assertfail.c b/libc/calls/assertfail.c
index 114ea89e4..508bd1347 100644
--- a/libc/calls/assertfail.c
+++ b/libc/calls/assertfail.c
@@ -23,6 +23,7 @@
 #include "libc/fmt/itoa.h"
 #include "libc/intrin/describebacktrace.internal.h"
 #include "libc/runtime/runtime.h"
+#include "libc/runtime/symbols.internal.h"
 
 /**
  * Handles assert() failure.
@@ -32,7 +33,7 @@ void __assert_fail(const char *expr, const char *file, int line) {
   sigset_t m = __sig_block();
   FormatInt32(ibuf, line);
   tinyprint(2, file, ":", ibuf, ": \e[31;1massert(", expr,
-            ") failed\e[0m (cosmoaddr2line ", program_invocation_name, " ",
+            ") failed\e[0m (cosmoaddr2line ", FindDebugBinary(), " ",
             DescribeBacktrace(__builtin_frame_address(0)), ")\n", NULL);
   __sig_unblock(m);
   abort();
diff --git a/libc/runtime/finddebugbinary.c b/libc/calls/finddebugbinary.c
similarity index 68%
rename from libc/runtime/finddebugbinary.c
rename to libc/calls/finddebugbinary.c
index c58e5556d..ff38f51a8 100644
--- a/libc/runtime/finddebugbinary.c
+++ b/libc/calls/finddebugbinary.c
@@ -20,13 +20,17 @@
 #include "libc/atomic.h"
 #include "libc/calls/blockcancel.internal.h"
 #include "libc/calls/calls.h"
+#include "libc/calls/syscall-sysv.internal.h"
 #include "libc/cosmo.h"
+#include "libc/dce.h"
+#include "libc/elf/def.h"
 #include "libc/elf/tinyelf.internal.h"
 #include "libc/errno.h"
 #include "libc/intrin/bits.h"
-#include "libc/macros.internal.h"
+#include "libc/intrin/directmap.internal.h"
+#include "libc/nt/memory.h"
+#include "libc/nt/runtime.h"
 #include "libc/runtime/runtime.h"
-#include "libc/runtime/symbols.internal.h"
 #include "libc/str/str.h"
 #include "libc/sysv/consts/map.h"
 #include "libc/sysv/consts/o.h"
@@ -38,24 +42,57 @@ static struct {
   char buf[PATH_MAX];
 } g_comdbg;
 
+static const char *kDbgExts[] = {
+    ".dbg",
+    ".com.dbg",
+#ifdef __aarch64__
+    ".aarch64.elf",
+#elif defined(__powerpc64__)
+    ".ppc64.elf",
+#endif
+};
+
+static int GetElfMachine(void) {
+#ifdef __x86_64__
+  return EM_NEXGEN32E;
+#elif defined(__aarch64__)
+  return EM_AARCH64;
+#elif defined(__powerpc64__)
+  return EM_PPC64;
+#elif defined(__riscv)
+  return EM_RISCV;
+#elif defined(__s390x__)
+  return EM_S390;
+#else
+#error "unsupported architecture"
+#endif
+}
+
 static bool IsMyDebugBinary(const char *path) {
-  void *map;
   int64_t size;
   uintptr_t value;
   bool res = false;
   int fd, e = errno;
+  struct DirectMap dm;
   BLOCK_CANCELATION;
   if ((fd = open(path, O_RDONLY | O_CLOEXEC, 0)) != -1) {
     // sanity test that this .com.dbg file (1) is an elf image, and (2)
     // contains the same number of bytes of code as our .com executable
     // which is currently running in memory.
     if ((size = lseek(fd, 0, SEEK_END)) != -1 &&
-        (map = mmap(0, size, PROT_READ, MAP_SHARED, fd, 0)) != MAP_FAILED) {
-      if (READ32LE((char *)map) == READ32LE("\177ELF") &&
-          GetElfSymbolValue(map, "_etext", &value)) {
+        (dm = sys_mmap(0, size, PROT_READ, MAP_SHARED, fd, 0)).addr !=
+            MAP_FAILED) {
+      if (READ32LE((char *)dm.addr) == READ32LE("\177ELF") &&
+          ((Elf64_Ehdr *)dm.addr)->e_machine == GetElfMachine() &&
+          GetElfSymbolValue(dm.addr, "_etext", &value)) {
         res = !_etext || value == (uintptr_t)_etext;
       }
-      munmap(map, size);
+      if (!IsWindows()) {
+        sys_munmap(dm.addr, size);
+      } else {
+        CloseHandle(dm.maphandle);
+        UnmapViewOfFile(dm.addr);
+      }
     }
     close(fd);
   }
@@ -65,20 +102,21 @@ static bool IsMyDebugBinary(const char *path) {
 }
 
 static void FindDebugBinaryInit(void) {
-  char *p = GetProgramExecutableName();
-  size_t n = strlen(p);
-  if ((n > 4 && READ32LE(p + n - 4) == READ32LE(".dbg")) ||
-      IsMyDebugBinary(p)) {
-    g_comdbg.res = p;
-  } else if (n + 4 < ARRAYLEN(g_comdbg.buf)) {
-    mempcpy(mempcpy(g_comdbg.buf, p, n), ".dbg", 5);
+  const char *comdbg;
+  if ((comdbg = getenv("COMDBG")) && IsMyDebugBinary(comdbg)) {
+    g_comdbg.res = comdbg;
+    return;
+  }
+  char *prog = GetProgramExecutableName();
+  for (int i = 0; i < ARRAYLEN(kDbgExts); ++i) {
+    strlcpy(g_comdbg.buf, prog, sizeof(g_comdbg.buf));
+    strlcat(g_comdbg.buf, kDbgExts[i], sizeof(g_comdbg.buf));
     if (IsMyDebugBinary(g_comdbg.buf)) {
       g_comdbg.res = g_comdbg.buf;
+      return;
     }
   }
-  if (!g_comdbg.res) {
-    g_comdbg.res = getenv("COMDBG");
-  }
+  g_comdbg.res = prog;
 }
 
 /**
diff --git a/libc/calls/unassertfail.c b/libc/calls/unassert.c
similarity index 93%
rename from libc/calls/unassertfail.c
rename to libc/calls/unassert.c
index bbd24a20b..137d61930 100644
--- a/libc/calls/unassertfail.c
+++ b/libc/calls/unassert.c
@@ -23,6 +23,7 @@
 #include "libc/fmt/itoa.h"
 #include "libc/intrin/describebacktrace.internal.h"
 #include "libc/runtime/runtime.h"
+#include "libc/runtime/symbols.internal.h"
 
 /**
  * Handles unassert() failure.
@@ -32,12 +33,12 @@
  * number of things. By doing this instead, we guarantee the backtrace
  * reported to the signal handler is clean and focused on the problem.
  */
-void __unassert_fail(const char *expr, const char *file, int line) {
+void(unassert)(const char *expr, const char *file, int line) {
   char ibuf[12];
   sigset_t m = __sig_block();
   FormatInt32(ibuf, line);
   tinyprint(2, file, ":", ibuf, ": \e[31;1munassert(", expr,
-            ") failed\e[0m (cosmoaddr2line ", program_invocation_name, " ",
+            ") failed\e[0m (cosmoaddr2line ", FindDebugBinary(), " ",
             DescribeBacktrace(__builtin_frame_address(0)), ")\n", NULL);
   __sig_unblock(m);
   notpossible;
diff --git a/libc/dlopen/dlopen.c b/libc/dlopen/dlopen.c
index 0636ac23d..83a3a7a4a 100644
--- a/libc/dlopen/dlopen.c
+++ b/libc/dlopen/dlopen.c
@@ -112,7 +112,7 @@ struct Loaded {
   char *base;
   char *entry;
   Elf64_Ehdr eh;
-  Elf64_Phdr ph[30];
+  Elf64_Phdr ph[25];
 };
 
 static struct {
@@ -277,8 +277,8 @@ static bool elf_slurp(struct Loaded *l, int fd, const char *file) {
   return true;
 }
 
-static bool elf_load(struct Loaded *l, const char *file, long pagesz,
-                     char *interp_path, size_t interp_size) {
+static dontinline bool elf_load(struct Loaded *l, const char *file, long pagesz,
+                                char *interp_path, size_t interp_size) {
   int fd;
   if ((fd = open(file, O_RDONLY | O_CLOEXEC)) == -1) {
     return false;
diff --git a/libc/intrin/unassertfail.c b/libc/intrin/unassert.c
similarity index 93%
rename from libc/intrin/unassertfail.c
rename to libc/intrin/unassert.c
index 0c5435a7a..0987615bf 100644
--- a/libc/intrin/unassertfail.c
+++ b/libc/intrin/unassert.c
@@ -18,7 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 
 // stub version of unassert() to keep the build a dag
-__attribute__((__weak__)) void __unassert_fail(const char *expr,
-                                               const char *file, int line) {
+__attribute__((__weak__)) void(unassert)(const char *expr, const char *file,
+                                         int line) {
   notpossible;
 }
diff --git a/libc/log/die.c b/libc/log/die.c
index 9870c8df9..f1f4fa497 100644
--- a/libc/log/die.c
+++ b/libc/log/die.c
@@ -22,6 +22,7 @@
 #include "libc/intrin/kprintf.h"
 #include "libc/log/internal.h"
 #include "libc/runtime/runtime.h"
+#include "libc/runtime/symbols.internal.h"
 #include "libc/str/str.h"
 
 /**
@@ -46,10 +47,9 @@ relegated wontreturn void __die(void) {
   strcpy(host, "unknown");
   gethostname(host, sizeof(host));
   kprintf("%serror: %s on %s pid %d tid %d has perished%s\n"
-          "cosmoaddr2line %s%s %s\n",
+          "cosmoaddr2line %s %s\n",
           __nocolor ? "" : "\e[1;31m", program_invocation_short_name, host,
-          getpid(), gettid(), __nocolor ? "" : "\e[0m", __argv[0],
-          endswith(__argv[0], ".com") ? ".dbg" : "",
+          getpid(), gettid(), __nocolor ? "" : "\e[0m", FindDebugBinary(),
           DescribeBacktrace(__builtin_frame_address(0)));
   _Exit(77);
 }
diff --git a/libc/log/minicrash.c b/libc/log/minicrash.c
index 585fe5a63..4cf427210 100644
--- a/libc/log/minicrash.c
+++ b/libc/log/minicrash.c
@@ -26,6 +26,7 @@
 #include "libc/log/internal.h"
 #include "libc/log/log.h"
 #include "libc/runtime/runtime.h"
+#include "libc/runtime/symbols.internal.h"
 #include "libc/str/str.h"
 
 /**
@@ -64,12 +65,12 @@ relegated dontinstrument void __minicrash(int sig, siginfo_t *si, void *arg) {
   gethostname(host, sizeof(host));
   kprintf(
       "%serror: %s on %s pid %d tid %d got %G%s code %d addr %p%s\n"
-      "cosmoaddr2line %s%s %lx %s\n",
+      "cosmoaddr2line %s %lx %s\n",
       __nocolor ? "" : "\e[1;31m", program_invocation_short_name, host,
       getpid(), gettid(), sig,
       __is_stack_overflow(si, ctx) ? " (stack overflow)" : "", si->si_code,
-      si->si_addr, __nocolor ? "" : "\e[0m", __argv[0],
-      endswith(__argv[0], ".com") ? ".dbg" : "", ctx ? ctx->uc_mcontext.PC : 0,
+      si->si_addr, __nocolor ? "" : "\e[0m", FindDebugBinary(),
+      ctx ? ctx->uc_mcontext.PC : 0,
       DescribeBacktrace(ctx ? (struct StackFrame *)ctx->uc_mcontext.BP
                             : (struct StackFrame *)__builtin_frame_address(0)));
 }
diff --git a/libc/log/oncrash_amd64.c b/libc/log/oncrash_amd64.c
index eab3c58a1..05b7aba70 100644
--- a/libc/log/oncrash_amd64.c
+++ b/libc/log/oncrash_amd64.c
@@ -74,8 +74,8 @@ static const char kFpuExceptions[6] forcealign(1) = "IDZOUP";
 
 relegated static void ShowFunctionCalls(ucontext_t *ctx) {
   kprintf(
-      "cosmoaddr2line %s%s %lx %s\n\n", __argv[0],
-      endswith(__argv[0], ".com") ? ".dbg" : "", ctx ? ctx->uc_mcontext.PC : 0,
+      "cosmoaddr2line %s %lx %s\n\n", FindDebugBinary(),
+      ctx ? ctx->uc_mcontext.PC : 0,
       DescribeBacktrace(ctx ? (struct StackFrame *)ctx->uc_mcontext.BP
                             : (struct StackFrame *)__builtin_frame_address(0)));
   ShowBacktrace(2, &(struct StackFrame){
diff --git a/libc/log/oncrash_arm64.c b/libc/log/oncrash_arm64.c
index eceeb654c..fd9e88e1b 100644
--- a/libc/log/oncrash_arm64.c
+++ b/libc/log/oncrash_arm64.c
@@ -229,8 +229,8 @@ static relegated void __oncrash_impl(int sig, struct siginfo *si,
   Append(b, " %s %s %s %s\n", names.sysname, names.version, names.nodename,
          names.release);
   Append(
-      b, " cosmoaddr2line %s%s %lx %s\n", __argv[0],
-      endswith(__argv[0], ".com") ? ".dbg" : "", ctx ? ctx->uc_mcontext.PC : 0,
+      b, " cosmoaddr2line %s %lx %s\n", FindDebugBinary(),
+      ctx ? ctx->uc_mcontext.PC : 0,
       DescribeBacktrace(ctx ? (struct StackFrame *)ctx->uc_mcontext.BP
                             : (struct StackFrame *)__builtin_frame_address(0)));
   if (ctx) {
diff --git a/libc/log/showcrashreports.c b/libc/log/showcrashreports.c
index 6c3e0620b..266d2b1ae 100644
--- a/libc/log/showcrashreports.c
+++ b/libc/log/showcrashreports.c
@@ -76,6 +76,7 @@ static void InstallCrashHandler(int sig, int flags) {
 void ShowCrashReports(void) {
   struct sigaltstack ss;
   static char crashstack[65536];
+  FindDebugBinary();
   ss.ss_flags = 0;
   ss.ss_size = sizeof(crashstack);
   ss.ss_sp = crashstack;
diff --git a/libc/tinymath/__math_oflow.c b/libc/tinymath/__math_oflow.c
index c9e56d044..02ea55841 100644
--- a/libc/tinymath/__math_oflow.c
+++ b/libc/tinymath/__math_oflow.c
@@ -28,7 +28,7 @@
 #include "libc/tinymath/internal.h"
 // clang-format off
 
-double __math_oflow(uint32_t sign)
+dontinstrument double __math_oflow(uint32_t sign)
 {
 	return __math_xflow(sign, 0x1p769);
 }
diff --git a/libc/tinymath/__math_oflowf.c b/libc/tinymath/__math_oflowf.c
index af6929dc1..9eff176ee 100644
--- a/libc/tinymath/__math_oflowf.c
+++ b/libc/tinymath/__math_oflowf.c
@@ -28,7 +28,7 @@
 #include "libc/tinymath/internal.h"
 // clang-format off
 
-float __math_oflowf(uint32_t sign)
+dontinstrument float __math_oflowf(uint32_t sign)
 {
 	return __math_xflowf(sign, 0x1p97f);
 }
diff --git a/libc/tinymath/__math_uflow.c b/libc/tinymath/__math_uflow.c
index bfe89b46a..a671044da 100644
--- a/libc/tinymath/__math_uflow.c
+++ b/libc/tinymath/__math_uflow.c
@@ -28,7 +28,7 @@
 #include "libc/tinymath/internal.h"
 // clang-format off
 
-double __math_uflow(uint32_t sign)
+dontinstrument double __math_uflow(uint32_t sign)
 {
 	return __math_xflow(sign, 0x1p-767);
 }
diff --git a/libc/tinymath/__math_uflowf.c b/libc/tinymath/__math_uflowf.c
index 29931ebfd..7f108f6f0 100644
--- a/libc/tinymath/__math_uflowf.c
+++ b/libc/tinymath/__math_uflowf.c
@@ -28,7 +28,7 @@
 #include "libc/tinymath/internal.h"
 // clang-format off
 
-float __math_uflowf(uint32_t sign)
+dontinstrument float __math_uflowf(uint32_t sign)
 {
 	return __math_xflowf(sign, 0x1p-95f);
 }
diff --git a/libc/tinymath/__math_xflow.c b/libc/tinymath/__math_xflow.c
index dd732eee8..145437f50 100644
--- a/libc/tinymath/__math_xflow.c
+++ b/libc/tinymath/__math_xflow.c
@@ -28,7 +28,7 @@
 #include "libc/tinymath/internal.h"
 // clang-format off
 
-double __math_xflow(uint32_t sign, double y)
+dontinstrument double __math_xflow(uint32_t sign, double y)
 {
 	return eval_as_double(fp_barrier(sign ? -y : y) * y);
 }
diff --git a/libc/tinymath/__math_xflowf.c b/libc/tinymath/__math_xflowf.c
index ae3fef854..13d9c7be9 100644
--- a/libc/tinymath/__math_xflowf.c
+++ b/libc/tinymath/__math_xflowf.c
@@ -28,7 +28,7 @@
 #include "libc/tinymath/internal.h"
 // clang-format off
 
-float __math_xflowf(uint32_t sign, float y)
+dontinstrument float __math_xflowf(uint32_t sign, float y)
 {
 	return eval_as_float(fp_barrierf(sign ? -y : y) * y);
 }